For myself, I think the problematic part of the XP system is that I can feel it pressuring me to write relatively inane, vapid things. If I recommend the "Perl Cookbook" again, that's almost a guaranteed 20 or 30 XP points. On the other hand, if I say something controversial (say, express skepticism about "inside-out objects"), then that's at best 5 points.

So the XP system appears to want me to repeat myself, cranking out mindless little things I can write in my sleep that most of us have heard already, but the things that are hard to write and actually require some thought, those would appear to be a waste of time.